// This file is part of Substrate.

// Copyright (C) 2018-2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Test setup for potential reentracy and lost updates of nested mutations.

#![cfg(test)]

use sp_runtime::{
	traits::IdentityLookup,
	testing::Header,
};
use sp_core::H256;
use sp_io;
use frame_support::parameter_types;
use frame_support::traits::StorageMapShim;
use frame_support::weights::{IdentityFee};
use crate::{
	self as pallet_balances,
	Pallet, Config,
};
use pallet_transaction_payment::CurrencyAdapter;

use crate::*;
use frame_support::{
	assert_ok,
	traits::{
		Currency, ReservableCurrency,
	}
};
use frame_system::RawOrigin;

type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<Test>;
type Block = frame_system::mocking::MockBlock<Test>;

fn last_event() -> Event {
	system::Pallet::<Test>::events().pop().expect("Event expected").event
}

frame_support::construct_runtime!(
	pub enum Test where
		Block = Block,
		NodeBlock = Block,
		UncheckedExtrinsic = UncheckedExtrinsic,
	{
		System: frame_system::{Pallet, Call, Config, Storage, Event<T>},
		Balances: pallet_balances::{Pallet, Call, Storage, Config<T>, Event<T>},
	}
);

parameter_types! {
	pub const BlockHashCount: u64 = 250;
	pub BlockWeights: frame_system::limits::BlockWeights =
		frame_system::limits::BlockWeights::simple_max(1024);
	pub static ExistentialDeposit: u64 = 0;
}
impl frame_system::Config for Test {
	type BaseCallFilter = ();
	type BlockWeights = BlockWeights;
	type BlockLength = ();
	type DbWeight = ();
	type Origin = Origin;
	type Index = u64;
	type BlockNumber = u64;
	type Call = Call;
	type Hash = H256;
	type Hashing = ::sp_runtime::traits::BlakeTwo256;
	type AccountId = u64;
	type Lookup = IdentityLookup<Self::AccountId>;
	type Header = Header;
	type Event = Event;
	type BlockHashCount = BlockHashCount;
	type Version = ();
	type PalletInfo = PalletInfo;
	type AccountData = ();
	type OnNewAccount = ();
	type OnKilledAccount = ();
	type SystemWeightInfo = ();
	type SS58Prefix = ();
	type OnSetCode = ();
}
parameter_types! {
	pub const TransactionByteFee: u64 = 1;
}
impl pallet_transaction_payment::Config for Test {
	type OnChargeTransaction = CurrencyAdapter<Pallet<Test>, ()>;
	type TransactionByteFee = TransactionByteFee;
	type WeightToFee = IdentityFee<u64>;
	type FeeMultiplierUpdate = ();
}

pub struct OnDustRemoval;
impl OnUnbalanced<NegativeImbalance<Test>> for OnDustRemoval {
	fn on_nonzero_unbalanced(amount: NegativeImbalance<Test>) {
		assert_ok!(Balances::resolve_into_existing(&1, amount));
	}
}
parameter_types! {
	pub const MaxLocks: u32 = 50;
}
impl Config for Test {
	type Balance = u64;
	type DustRemoval = OnDustRemoval;
	type Event = Event;
	type ExistentialDeposit = ExistentialDeposit;
	type AccountStore = StorageMapShim<
		super::Account<Test>,
		system::Provider<Test>,
		u64,
		super::AccountData<u64>,
	>;
	type MaxLocks = MaxLocks;
	type WeightInfo = ();
}

pub struct ExtBuilder {
	existential_deposit: u64,
}
impl Default for ExtBuilder {
	fn default() -> Self {
		Self {
			existential_deposit: 1,
		}
	}
}
impl ExtBuilder {

	pub fn existential_deposit(mut self, existential_deposit: u64) -> Self {
		self.existential_deposit = existential_deposit;
		self
	}

	pub fn set_associated_consts(&self) {
		EXISTENTIAL_DEPOSIT.with(|v| *v.borrow_mut() = self.existential_deposit);
	}

	pub fn build(self) -> sp_io::TestExternalities {
		self.set_associated_consts();
		let mut t = frame_system::GenesisConfig::default().build_storage::<Test>().unwrap();
		pallet_balances::GenesisConfig::<Test> {
			balances: vec![],
		}.assimilate_storage(&mut t).unwrap();
		let mut ext = sp_io::TestExternalities::new(t);
		ext.execute_with(|| System::set_block_number(1));
		ext
	}
}

#[test]
fn transfer_dust_removal_tst1_should_work() {
	ExtBuilder::default()
		.existential_deposit(100)
		.build()
		.execute_with(|| {
			// Verification of reentrancy in dust removal
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 1, 1000, 0));
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 2, 500, 0));

			// In this transaction, account 2 free balance
			// drops below existential balance
			// and dust balance is removed from account 2
			assert_ok!(Balances::transfer(RawOrigin::Signed(2).into(), 3, 450));

			// As expected dust balance is removed.
			assert_eq!(Balances::free_balance(&2), 0);

			// As expected beneficiary account 3
			// received the transfered fund.
			assert_eq!(Balances::free_balance(&3), 450);

			// Dust balance is deposited to account 1
			// during the process of dust removal.
			assert_eq!(Balances::free_balance(&1), 1050);

			// Verify the events
			// Number of events expected is 8
			assert_eq!(System::events().len(), 11);

			assert!(
				System::events().iter().any(
					|er|
					er.event == Event::pallet_balances(
						crate::Event::Transfer(2, 3, 450),
					),
				),
			);

			assert!(
				System::events().iter().any(
					|er|
					er.event == Event::pallet_balances(
						crate::Event::DustLost(2, 50)
					),
				),
			);
		}
	);
}

#[test]
fn transfer_dust_removal_tst2_should_work() {
	ExtBuilder::default()
		.existential_deposit(100)
		.build()
		.execute_with(|| {
			// Verification of reentrancy in dust removal
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 1, 1000, 0));
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 2, 500, 0));

			// In this transaction, account 2 free balance
			// drops below existential balance
			// and dust balance is removed from account 2
			assert_ok!(Balances::transfer(RawOrigin::Signed(2).into(), 1, 450));

			// As expected dust balance is removed.
			assert_eq!(Balances::free_balance(&2), 0);

			// Dust balance is deposited to account 1
			// during the process of dust removal.
			assert_eq!(Balances::free_balance(&1), 1500);

			// Verify the events
			// Number of events expected is 8
			assert_eq!(System::events().len(), 9);

			assert!(
				System::events().iter().any(
					|er|
					er.event == Event::pallet_balances(
						crate::Event::Transfer(2, 1, 450),
					),
				),
			);

			assert!(
				System::events().iter().any(
					|er|
					er.event == Event::pallet_balances(
						crate::Event::DustLost(2, 50),
					),
				),
			);
		}
	);
}

#[test]
fn repatriating_reserved_balance_dust_removal_should_work() {
	ExtBuilder::default()
		.existential_deposit(100)
		.build()
		.execute_with(|| {
			// Verification of reentrancy in dust removal
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 1, 1000, 0));
			assert_ok!(Balances::set_balance(RawOrigin::Root.into(), 2, 500, 0));

			// Reserve a value on account 2,
			// Such that free balance is lower than
			// Exestintial deposit.
			assert_ok!(Balances::reserve(&2, 450));

			// Transfer of reserved fund from slashed account 2 to
			// beneficiary account 1
			assert_ok!(Balances::repatriate_reserved(&2, &1, 450, Status::Free), 0);

			// Since free balance of account 2 is lower than
			// existential deposit, dust amount is
			// removed from the account 2
			assert_eq!(Balances::reserved_balance(2), 0);
			assert_eq!(Balances::free_balance(2), 0);

			// account 1 is credited with reserved amount
			// together with dust balance during dust
			// removal.
			assert_eq!(Balances::reserved_balance(1), 0);
			assert_eq!(Balances::free_balance(1), 1500);

			// Verify the events
			// Number of events expected is 10
			assert_eq!(System::events().len(), 10);

			assert!(
				System::events().iter().any(
					|er|
					er.event == Event::pallet_balances(
						crate::Event::ReserveRepatriated(2, 1, 450, Status::Free),
					),
				),
			);

			assert_eq!(
				last_event(),
				Event::pallet_balances(crate::Event::DustLost(2, 50)),
			);

		}
	);
}
